Benzoyl butyric acid derivates as photosensitizers for unsaturated materials

ABSTRACT

The invention relates to gamma -Hydroxy- gamma -phenyl- gamma -benzoylbutyric acids, the esters and amides thereof, which are useful photosensitisers for the photopolymerisation of polymerisable compounds or compound mixtures including mixtures of unsaturated polyesters and copolymerisable monomeric compounds.

United States Patent [1 1 Rudolph et al.

[ Oct. 28, 1975 BENZOYL BUTYRIC ACID DERIVATES AS PHOTOSENSITIZERS FOR UNSATURATED MATERIALS Inventors: Hans Rudolph, Krefled-Bockum;

Hans-Georg Heine; Karl Fuhr, both of Krefeld; Hermann Schnell, Krefeld-Uerdingen, all of Germany Assignee: Bayer Aktiengesellschaft, Germany Filed: July 10, 1974 Appl. Non. 487,381

Related US. Application Data Division of Ser. No. 867,939, Oct. 20, 1969, Pat. No. 3,824,284.

Foreign Application Priority Data Nov. 6, 1968 Germany 1807301 US. Cl.. 204/159.15; 204/159.23; 260/89.5 A; 260/93.5 A; 260/343.6; 260/473 A; 260/473 R; 260/520; 260/559; 260/861; 260/864 Int. Cl. C08F 8/00; C08F 2/46; C08F 4/00 Field of Search 204/159.l5, 159.23; 260/861, 93.5 A, 520; 117/9331 [56] References Cited UNITED STATES PATENTS 3,657,088 4/1972 Heine et al. 204/159.23 3,689,565 9/1972 Hoffman et al..... 204/159.23 3,824,284 7/1974 Rudolph et al. 204/l59.23

OTHER PUBLICATIONS Yokoyami et al., The Peracid Oxidation of Victories, IV., Bull. Chem. Soc., Japan; Vol. 38, No. 9, pp. 1501-1503, (1965).

Primary ExaminerRichard B. Turner Attorney, Agent, or Firm-Connolly and Hutz [57] ABSTRACT 10 Claims, No Drawings BENZOYL BUTYRIC ACID DERIVATES AS PHOTOSENSITIZERS FOR UNSATURATED MATERIALS This application is a division of application Ser. No. 867,939 filed Oct. 20, 1969, now U.S. Pat. No. 3,824,284, issued July 16, 1974.

The object of the present invention are 'y-hydroxy-yphenyl-y-benzoylbutyric acid compounds of formula in which R and R are identical or different and represent hydrogen, lower alkyl having 1 to about 4 carbon atoms, methoxy or halogen, R represents OH, OR., or optionally substituted -NH and R represents lower alkyl having 1 to 4 carbon atoms, and the lactones of formula Examples of such compounds are:

'y-Hydroxy-y-phenyl-y-benzoylbutyric acid, -yHydroxy-y-phenyl-'y-benzoylbutyric acid-y-lactone -y-Hydroxy-y-phenyl-y-benzoylbutyric acid methyl ester a-( B-Carbonamido-ethyl )-benzoin a-(B-Carbonamidcrethyl)-4,4'-dimethylbenzoin a-(B-Carbonamido-ethyl)-4,4'-dimethoxybenzoin a-(B-Carbonamido-ethyl)-4,4'-dichlorobenzoin and a- [B-( N-Methoxymethyl )-carbonamido-ethyl] -benzoin prolonged storage in daylight, should be mentioned; furthermore, some of the compounds known as sensitisers are difficult to obtain.

Against this, the compounds according to the invention are easily obtainable, reactive substances, mixtures of which with polymerisable compounds are storagestable for particularly long periods in the dark. The compounds according to the invention also have satisfactorily as regards discolouration of the polymers in daylight. Because of their content of reactive groups they can also be easily built chemically into the compounds to be polymerised, for example into unsaturated polyesters.

When the compounds are used as photosensitisers they are appropriately employed in amounts of from about 0.1 to about 5 per cent by Weight, preferably of from about 0.5 to about 2.5 per cent by weight, either by themselves or mixed with one another or mixed with photosensitisers of a different nature. Suitable polymerisable compounds are all substances of which the carbon-carbon double bonds are activated by, for example, halogen atoms or carbonyl, cyanide, carboxyl, ester, amide, ether or aryl groups as well as carbon double bonds and carbon triple bonds. As examples there may be mentioned: styrene, vinyl toluene, divinyl benzene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl methyl ketone, acrylic and methacrylic acid, esters thereof such as the methyl, ethyl and allyl ester, their amides and nitriles, and other allyl esters, such as allyl acetate, phthalic acid diallyl ester and phosphoric acid triallyl ester, and mixtures of such compounds Moulding and coating compositions of mixtures, stabilised in the usual manner, of unsaturated polyesters and copolymerisable monomeric compounds can be used particularly advantageously, and unsaturated polyesters are here, as usual, to be understood as polycondensation products of a,B-unsaturated dicarboxylic acids such as, for example, maleic acid and fumaric acid, with polyols such as, for example, ethylene glycol and propanediol-l,2. A part of the unsaturated acids can be replaced by saturated acids, such as, for exam- C melting point l09-l 14 boiling point l80 (0.2 mm Hg) melting point 74-77 melting point l52l53 melting point l55l56 melting point l48l49 melting point l52l53 melting point 98-99 ple, phthalic acid. Further modifications are possible through building-in monobasic acids and monohydric alcohols. So-called air-drying moulding compositions which in addition to the radicals of a,B-unsaturated dicarboxylic acids also contain B,-y-unsaturated ether radicals can also be employed, either as a constituent of the polyesters or as a constituent of further components of the mixture.

By copolymerisable monomeric compounds there are to be understood that unsaturated compounds which are usual in polyester technology, having vinyl groups which are optionally substituted in the a-posin, or allyl groups which are optionally substituted in B-position, preferably styrene.

lhe photopolymerisable compounds or mixtures can stabilised by the addition of usual inhibitors, such as :lroquinone, in the known amounts. Polymerisation :alysts, for example peroxides, can optionally also be njointly employed in the usual manner. In conjuncn with the use of ketone hydroperoxides, metal comunds, for example cobalt naphthenate, can be added accelerating complete cure. In this case the storage bility of the photopolymerisable compositions is adttedly lowered. It is therefore advisable when manuturing lacquer coatings to work in accordance with so-called active primer method in which the coating nposition is applied onto a peroxide-containing er which has beforehand been applied to the subate.

t is particularly advantageous to employ the new npounds in coating compositions to which paraffin wax or wax-like substances are added which float to surface at the start of the polymerisation and preit the inhibiting action of atmospheric oxygen.

:1 order to protect light-sensitive substrates, for exple light timbers, small amounts of customary ultralet absorbers may be added to the moulding and lting compositions without the reactivity being sigicantly impaired. Furthermore, small amounts of :tomary carriers and fillers as well as agents for conring thixotropy, such as glass fibres, synthetic fibres,

ca and talcum, can be present during the )topolymerisation. \s radiation sources for carrying out the )topolymerisation, it is possible to use natural sunit or artificial radiation sources of which the emisn lies in the range of about 250 to about 500 mu, ferably from about 300 to about 400 mu. Mercury our lamps, xenon lamps or tungsten lamps are for imple suitable. The compositions also rapidly cure to e colourless moulded and coated articles under the 'aviolet and visible radiation of low energy fluoresit lamps emitting rays of about 300 to about 580 mu. Vhen manufacturing mouldings from the sensitised npositions it proves particularly advantageous to be e to cure the compositions by appropriately metered idiation without a significant heating effect, as a reof which larger mouldings can also be obtained free :racks. In the absence of peroxides and metal acceltors the cure can also optionally be interrupted )ugh placing the material in darkness and comted at any desired time after storing the prepolymers 5 obtained.

he new compounds can be manufactured in a manwhich is in itself known by addition of acrylic acid ivatives to benzoins and optionally further reaction he adducts.

-I-Iydroxy-y-phenyl-y-benzoylbutyric acid can for mple be obtained in accordance with the following ruction: ml of acrylic acid ethyl ester and 50 ml vO aqueous sodium hydroxide solution are added 'OC to a solution of 21.2 g of benzoin in 200 ml of .-butanol. Thereafter the reaction mixture is aled to cool and diluted with a 5-fold amount of waand unreacted benzoin is filtered off. The filtrate is :fully acidified and extracted with ether. After the al working-up a crude product is obtained from ch 23 g of crystals separate out after addition of zene. After recrystallisation from ether/petroleum 4 ether 8.5 g of white crystals are obtained. Melting point 109 114C (cyclisation to give the lactone).

'y-I-Iydroxy-y-phenyl-y-benzoylbutyric acid-'y-lactone can for example be obtained in accordance with the following instruction: 43 g of acrylic acid ethyl ester and 50 m1 of 10 aqueous sodium hydroxide solution are added to a solution of 25 g of benzoin in 200 ml of tert.-butanol at C. Thereafter the reaction solution is mixed with 1 l of water and cooled. The unreacted benzoin is filtered off and the alkaline filtrate is acidified. After the usual working-up 15.6 g of crude acid are obtained and are dissolved in benzene and filtered through silica gel. 9.3 g of oil lactone can be obtained in a pure form by distillation. Boiling point C (0.2 mm g); rl 15895-15907.

a-(,B-Carbonamido-ethyl)-benzoin can for example be obtained in accordance with the following instruction: a mixture of 12 g of acrylonitrile and 30 g of 10 potassium hydroxide solution is added at 60C to a solution of 42.5 g of benzoin in 600 g of tert.-butanol. Thereafter the mix is allowed to cool and is introduced into 3 l of ice water, and the precipitate which has separated out is filtered off and rinsed with water. After recrystallisation from ethyl acetate 25 g of oz-(B-carbonamido-ethyl)-benzoin, melting point 152 153C, are obtained.

The amide can however also for example be obtained in the following manner: a mixture of 7.1 g of acrylamide and 30 ml of IO sodium hydroxide solution is added at 60C to a solution of 21.2 g of benzoin in 250 ml of tert.-butanol. Thereafter the mix is allowed to cool and is introduced into 3 litres of ice water, and the precipitate which has separated out is filtered off and rinsed with water. The precipitate is taken up in benzene and filtered through silica gel. Hereupon 13.5 g of unchanged benzoin and 7.3 g of the amide described above (melting point 152 153C) are obtained.

The methyl ester can for example be manufactured in the following manner: 3 g of the free acid are dissolved in 10 ml of ether, mixed with excess ethereal diazomethane solution and left to stand for 15 minutes at room temperature. After evaporation of the ether and recrystallisation of the residue from ether/petroleum ether, 1.7 g of y-hydroxy-y-phenyl-'y-benzoylbutyric acid-methyl ester are obtained. Melting point 74 77C.

EXAMPLE 1 10 g of extracted and freshly distilled acrylic acid methyl ester are mixed with 0.1 g of a-(B-carbonamido-ethyl)-benzoin.

The mixture is illuminated with a mercury vapour high pressure lamp (Philips HPK 125 W/L) through quartz glass in a waterbath at 24C, at a distance of 10 cm. The solution of the sensitiser in the monomer is at the same time contained in a quartz glass of internal diameter 1.7 cm under a nitrogen atmosphere. The illumination time is 2 /2 minutes. Immediately after illumination the quartz glass is introduced into an acetone/solid carbon dioxide mixture in order to prevent a thermal polymerisation. The" solution of the polymer in the monomer and the solid polymer particles which are present on the inside of the quartz glasses on the side facing the mercury vapour high pressure lamp are transferred into a small round flask with the aid of small amounts of a solvent (methylene chloride).

Thereafter unpolymerised monomeric constituents and the solvent are distilled off in a rotating evaporator.

After drying in vacuo to constant weight at 60C, the quantity of polymer amounts to 12.8 per cent by weight.

If the sensitiser is absent, the quantity of polymer is less than 0.1

EXAMPLE 2 An unsaturated polyester manufactured by condensing 152 parts by weight of maleic anhydride, 141 parts by weight of phthalic anhydride and 195 parts by weight of propanedioll ,2 is mixed with 0.045 parts by weight of hydroquinone and dissolved in styrene to give a 65 per cent by weight solution.

2 parts by weight of two different known photosensitisers on the one hand and of three different photosensitisers according to the invention on the other hand are added to 100 parts by weight at a time of this form in which the resin is supplied, and the mixtures are stored at 60C, with exclusion of light, until they gel. Table 1 gives the sensitisers and the storage stability values at 60C.

Table 1 Storage stability in the dark of the form in which a typical polyester resin is supplied, with the addition of 2 parts by weight of sensitiser.

Sensitiser Storage Stability at 60C Benzoin less than 1 day Benzoin ethyl ether less than 1 day more than days more than 10 days EXAMPLE 3 parts by weight of styrene, 1 part by weight of a 10 per cent by weight solution of paraffin (melting point 52 53C) in toluene, as well as benzoin or photosensitisers according to the invention in equimolar amounts, are mixed into 100 parts by weight at a time of the form in which the resin is supplied which has been described in example 2. The solutions thus obtained are applied to glass plates by means of a film spreader (500 p.) and are illuminated with radiation from a fluorescent lamp (Osram L 4OW/70-1) at a distance of 5 cm.

Table 2 gives the times for the paraffin to float to the surface and the times until a pencil hardness 6 H is 1. In the process of preparing coatings and molded bodies by photopolymerizing a mixture of at least one ethylenically unsaturated polymerizable compound and a photosensitizer by irradiating said mixture with a radiation source, the improvement which comprises 1 employing 0.1 to 5% by weight, based on said ethylenically unsaturated compound of a photosensitizer of the formula wherein R and R are identical or different and are selected from the group consisting of hydrogen, alkyl having 1 to 4 carbon atoms, methoxy and halogen.

2. The process of claim 1 wherein the photosensitizer is employed in an amount of 0.5 to 2.5% by weight based on the ethylenically unsaturated compound.

3. The process of claim 1 wherein R and R of said formula are hydrogen.

4. The process of claim 1 .wherein said at least one ethylenically unsaturated compound is a mixture of an unsaturated polyester which is the condensation product of an a,B-dicarboxylic acid and a polyol and an ethylenically unsaturated copolymerizable monomer.

5. The process of claim 1 wherein each ethylenically unsaturated compound is selected from the group consisting of styrene, vinyl toluene, divinylbenzcne, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl methyl ketone, acrylic acid, methacrylic acid, acrylic acid methyl ester, methacrylic acid methyl ester, acrylic acid ethyl ester, methacrylic acid ethyl ester, acrylic acid allyl ester, methacrylic acid allyl ester, acrylic acid amide, methacrylic acid amide, acrylic acid nitrile, methacrylic acid nitrile, allyl acetate, phthalic acid diallyl ester, phosphoric acid triallyl ester and mixtures thereof.

6. A mixture of at least one ethylenically unsaturatated polymerizable compound and from 0.1 to 5% by weight, based on said ethylenically unsaturated compound, of a photosensitizer of the formula 7 wherein R, and R are identical or different and are selected from the group consisting of hydrogen, alkyl having 1 to 4 carbon atoms, methoxy and halogen.

7. The composition of claim 6 wherein the photosensitizer is employed in an amount of 0.5 to 2.5% by weight based on the ethylenically unsaturated compound.

8. The composition of claim 6 wherein R and R of said formula are hydrogen.

9. The composition of claim 6 wherein said at least one ethylenically unsaturated compound is a mixture of an unsaturated polyester which is the condensation product of an a,B-dicarboxylic acid and a polyol and an ethylenically unsaturated copolymerizable monomer.

10. The composition of claim 6 wherein each ethylenically unsaturated compound is selected from the group consisting of styrene, vinyl toluene, divinylbenzene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl methyl ketone, acrylic acid, methacrylic acid, acrylic acid methyl ester, methacrylic acid methyl ester, acrylic acid ethyl ester, methacrylic acid ethyl ester, acrylic acid allyl ester, methacrylic acid allyl ester, acrylic acid amide, methacrylic acid amide, acrylic acid nitrile, methacrylic acid nitrile, allyl acetate, phthalic acid diallyl ester, phosphoric acid triallyl ester and mixtures thereof. 

1. IN THE PROCESS OF PREPARING COATINGS AND MOLDED BODIES BY PHOTOPOLYMERIZING A MIXTURE OF AT LEAST ONE ETHYLENICALLY UNSATURATED POLYMERIZABLE COMPOUND AND A PHOTOSENSITIZER BY IRRADIATING SAID MIXTURE WITH A RADIATION SOURCE, THE IMPROVEMENT WHICH COMPRISES EMPLOYING 0.1 TO 5% BY WEIGHT, BASED ON SAID ETHYLENICALLY UNSATURATED COMPOUND, OF A PHOTOSENSITIZER OF THE FORMULA
 2. The process of claim 1 wherein the photosensitizer is employed in an amount of 0.5 to 2.5% by weight based on the ethylenically unsaturated compound.
 3. The process of claim 1 wherein R1 and R2 of said formula are hydrogen.
 4. The process of claim 1 wherein said at least one ethylenically unsaturated compound is a mixture of an unsaturated polyester which is the condensation product of an Alpha , Beta -dicarboxylic acid and a polyol and an ethylenically unsaturated copolymerizable monomer.
 5. The process of claim 1 wherein each ethylenically unsaturated compound is selected from the group consisting of styrene, vinyl toluene, divinylbenzene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl methyl ketone, acrylic acid, methacrylic acid, acrylic acid methyl ester, methacrylic acid methyl ester, acrylic acid ethyl ester, methacrylic acid ethyl ester, acrylic acid allyl ester, methacrylic acid allyl ester, acrylic acid amide, methacrylic acid amide, acrylic acid nitrile, methacrylic acid nitrile, allyl acetate, phthalic acid diallyl ester, phosphoric acid triallyl ester and mixtures thereof.
 6. A mixture of at least one ethylenically unsaturatated polymerizable compound and from 0.1 to 5% by weight, based on said ethylenically unsaturated compound, of a photosensitizer of the formula
 7. The composition of claim 6 wherein the photosensitizer is employed in an amount of 0.5 to 2.5% by weight based on the ethylenically unsaturated compound.
 8. The composition of claim 6 wherein R1 and R2 of said formula are hydrogen.
 9. The composition of claim 6 wherein said at least one ethylenically unsaturated compound is a mixture of an unsaturated polyester which is the condensation product of an Alpha , Beta -dicarboxylic acid and a polyol and an ethylenically unsaturated copolymerizable monomer.
 10. The composition of claim 6 wherein each ethylenically unsaturated compound is selected from the group consisting of styrene, vinyl toluene, divinylbenzene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl methyl ketone, acrylic acid, methacrylic acid, acrylic acid methyl ester, methacrylic acid methyl ester, acrylic acid ethyl ester, methacrylic acid ethyl ester, acrylic acid allyl ester, methacrylic acid allyl ester, acrylic acid amide, methacrylic acid amide, acrylic acid nitrile, methacrylic acid nitrile, allyl acetate, phthalic acid diallyl ester, phosphoric acid triallyl ester and mixtures thereof. 